//
// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license.
//
// Microsoft Bot Framework: http://botframework.com
//
// Bot Framework Emulator Github:
// https://github.com/Microsoft/BotFramwork-Emulator
//
// Copyright (c) Microsoft Corporation
// All rights reserved.
//
// MIT License:
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED ""AS IS"", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

let singleton: AriaAlertService;
class AriaAlertService {
  constructor() {
    singleton = this;
  }

  /** Creates an alert and inserts it into the DOM */
  public alert(msg: string): void {
    if (!msg) {
      return;
    }
    const prevAlert = document.querySelector('span#alert-from-service');
    prevAlert && prevAlert.remove();
    const alert = document.createElement('span');
    alert.innerText = msg;
    alert.setAttribute('id', 'alert-from-service');
    alert.setAttribute('role', 'alert');
    alert.setAttribute('style', 'position: absolute; top: -9999px; overflow: hidden;');
    document.body.appendChild(alert);

    setTimeout(() => {
      alert.setAttribute('aria-hidden', 'true');
    }, 5000);
  }
}

/** Creates invisible alerts to be read by screen reader technologies */
export const ariaAlertService = singleton || new AriaAlertService();
